AU614889B2

AU614889B2 - Vibratory sieve bends

Info

Publication number: AU614889B2
Application number: AU46094/89A
Authority: AU
Inventors: Gregory Eldridge
Original assignee: SCREEN MANAGEMENT CONSULTANTS
Current assignee: Johnson Filtration Systems Australia Pty Ltd
Priority date: 1989-01-11
Filing date: 1989-12-11
Publication date: 1991-09-12
Anticipated expiration: 2009-12-11
Also published as: AU4609489A; GB8928644D0; GB2227294A; GB2227294B

Description

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614889 COMMONWEALTH OF AUSTRALIA The Patents Act 1952 Name of Applicant(s): Address of Applicant(s): SCREEN MANAGEMENT CONSULTANTS PTY

LTD

88 BRICKYARD ROAD GEEBUNG, QUEENSLAND, 4034,

AUSTRALIA

GREGORY ELDRIDGE G.R. CULLEN COMPANY, Patent Trade Mark Attorneys, 79 Eagle Street, Brisbane, Qld. 4000, Australia.

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Actual Inventor(s): Address for Service: COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED:

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VIBRATORY SIEVE BENDS The following statement is a full description of the invention including the best method of performing it known to us:

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The present invention relates to sieve bends and in particular to vibratory sieve bends.

Sieve bends are extremely effective devices for solid-solid separation and for dewatering of slurried suspensions, and are used extensively in a multitude of industries. Such devices comprise a screen of wire mesh which is curved to a predetermined radius of curvative so as, in profile, to form an arc of a circle. In use, the screen is generally supported at a relatively steep angle with respect to the horizontal such that when material is gravity fed down over it, the flow of material is effectively separated into one portion called the underflow which passes through the screen and another portion called the overflow which passes over the screen.

15 In order to increase the efficiency of these sieve bends, various proposals have been made for vibrating the sieve bends during operation. One such proposal comprises an arrangement whereby a striker repeatedly hits the screen to set up vibrations therein. This, however, has the .20 disadvantage that a relatively high concentrated force is continually being applied to the same region of the screen with the result that the screen ruptures after a relatively short life span. Another proposal comprises an arrangement whereby a partition plate is welded to a central portion of the screen and a vibrator is fitted to this plate. In operation this sets up a continuous uniform vibration at the 5500 0 0

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centre of the screen. However the vibrations decrease outwardly from the centre with the result that the amount of vibration at the edge of the screen is considerably less than at the centre and the relative degree of separation along the edge regions of the screen is substantially diminished. Such an arrangement is also subject to premature fatigue and eventual rupture as in the previous embodiment.

It is therefore an object of the present invention to provide a vibratory apparatus for sieve bends which obviates or at least minimises the aforementioned disadvantages.

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S. 5 r S d Accordingly, the present invention provides apparatus for vibrating a sieve bend comprising a housing in which a weightBd rotatable shaft is located for the purpose of vibrating the housing upon rotation, and at least one diaphragm vibrationally connected to said housing and extending at right angles to the shaft; wherein a sieve bend is connectable to the apparatus in such a manner that, in use, the housing projects below the sieve across its width in vibratory contact therewith, and the at least one diaphragm extends below the sieve along its length in vibratory contact therewith; the construction and arrangement being such that, in use, rotation of the shaft causes vibrational motion to be evenly transmitted to the length and width of the sieve bend.

In order to ensure that the vibrational energy given out by the rotating shaft is transmitted essentially in r. ill I II I 4 its entirety to the sieve bend, the entire apparatus is preferably suspended so that it substantially floats with respect to a supporting framework. This may be achieved by suspending the apparatus by means of chains or similar flexible members to blocks of resiliently deformable material attached to the support frame.

The vibratory apparatus itself may be contained within an open box structure which is constructed to provide support for the sieve bend and to channel the feed material to the sieve and separated fractions away therefroi. In such an arrangement, the box structure itself will be suspended to the supporting framework by way of resiliently deformable connectors. For additional prevention of ene-gy loss into the box itself; the connections between the apparatus and the 15 box are ideally also fabricated from resiliently deformable material.

The preferred resiliently deformable material is polyurethane but other plastics or rubber materials may equally well be used.

20 The housing in which the weighted shaft is located, is preferably a tubular pipe fabricated, for instance, from

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mild steel. An axial bearing is provided at each end of the housing for support of the shaft which extends to a suitable drive. When contained within the open box structure, the *25 pipe is vibrationally insulated from the box by a ring of resiliently deformable material between the side walls of the I ?lll :nP:ii;iil;_- i ri~~l~ box and the pipe.

The weighted shaft may assume any configuration necessary to achieve the desired end result of setting up vibrations within the housing. This is preferably achieved by the use of a square profile shaft which has one or more weights added to it, preferably adjacent one end thereof.

Rotation of such a shaft sets up an imbalance which is converted to vibratory motion in the housing.

Rotation of the shaft may be effected by a high rpm motor which is connected to the end of the shaft, on the exterior of the housing by a belt and pulley arrangement.

The at least one diaphragm may comprise a mild o00o steel or similar plate structure which is welded or otherwise vibrationally connected to the housing. Preferably, the at 15 least one diaphragm extends almost totally around the housing in a plane at right angles to the shaft contained therein.

The diaphragm cannot generally extend right around the housing since the housing has one region which is adapted for 00.*.0 contact with the sieve bend and it is in this region which the diaphragm does not extend. The number of diaphragms employed will usually be determined by the size of the *o apparatus and may be from one to several. Generally, however, there will be about two which are equally spaced 0o0*i from the ends of the housing and from one another. In the *25 case where the apparatus is contained within an open box, the side walls of the box could function as diaphragms also i f.

i i i ~;!il4 ;i I- however, as mentioned above, such side walls are usually insulated vibrationally from the apparatus, and the amount of vibration which can be transmitted in this region will be minimal.

Preferably the at least one diaphragm is also connected to supports which extend parallel to the tubular housing on each side thereof. These supports may be tubular or solid rods which lie in the arc of the sieve bend to be used with the apparatus. When the apparatus is contained in an open box structure, these supports are preferably also supported in resiliently deformable material in the side walls of the box. Although there may preferably be two supports, any number of supports may, in practice, be o included. The-se supports provide additional transmission of vibratory motion to the sieve bend and thus aid in evening the vibration throughout the entire screening surface.

In situations where very high frequency vibration is required, an additional vibrator may be included in the apparatus. Such a vibrator may conveniently be located on a plate afixed to the at least one diaphragm. Preferably, :there will be at- least two diaphragms to enable adequate and even transmission of the vibrations to the sieve bend. When the apparatus is contained within a box as described above, a *rearwardly facing wall of the box may function as the plate I to which the vibrator is attached. The vibrator may take the form of an electro-magnetic oscillator.

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i 1 I I 7 By the use of such an apparatus, vibration is evenly transmitted.to the entire screening surface of a sieve bend by way of the housing and diaphragms, thereby obviating the premature problems of fatigue found in previous vibratory arrangements. Additionally, by the suspension of the apparatus in a substantially free-floating manner, loss of energy throughout the entire screening apparatus is reduced to a minimum and substantial energy savings are achieved.

The invention also extends to a combination of such apparatus with a sieve bend.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which:- Fig. 1 is a front elevational view of an apparatus according to the present invention, contained within a box and suspended by a framework; Fig. 2 is a rear elevational view of the apparatus of Fig. 1; Fig. 3 is a side elevational view of the apparatus 210 of Fig. 1;

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Fig. 4 is a close-up view of a portion of the apparatus of Fig. 1; and Fig. 5 is a side-on perspective 'of a weighted shaft in use in the apparatus of Fig. 1.

Referring to the drawings, in all of which like parts are designated- by like reference numerals, the I apparatus comprises a mild steel tubular housing 10 (see Fig.

4) in which a weighted square profile shaft 11 is fitted for rotation. A weight lla is welded to the shaft adjacent one end thereof. The shaft 11 is suspended in bearings 12, 13 located within enclosures 14, 15 on the exterior sides of opposite walls of an open mild steel box structure 16.

Two diaphragms '17, 18 of mild steel plate are welded to the housing 10 and extend the entire screen supporting length of the apparatus. At each end, the diaphragms are welded to additional tubular supports only one of which, viz no. 19, can be seen in Fig. 2. The ends of the supports are connected to the walls of the box structure 16 through polyurethane linkages 20, 21 formed by setting liquid polyurethane between an annular containment ring 22 welded to the exterior box wall and the outer end surface of the .0 additional tubular supports. Such a connection reduces the amount of vibration transmitted from the additional tubular supports to the box structure.

A sieve bend 23 is supported in an inclined plane '02.0 atop the housing 11, additional supports 19 and diaphragms '00: 17, 18. The sieve bend 23 is held in position by rigid strip securements 24, 25 formed from moulded polyurethane which overlay and clamp the sieve bend to the said housing supports and diaphragm, as well as to the side walls of the open box.

The sieve bend 23 may be readily removed for maintenance or replacement by unfastening appropriate fastening means 26 9 located along the upper surface of the polyurethane securements. Such fastening means may comprise bolts with associated squared profiled washer-type retainers.

A motor 27 having a 1,230 rmp rating and a 1 mm amplitude, is connected to the weighted shaft 11 by way of a belt 28 and pulley 29. The motor is secured to a framework which suspends the entire apparatus and box so that the apparatus and box are essentially floating. The suspending units comprise four chains 31 connected to polyurethane blocks 32 attached through cupped polyurethane containing holders 33 atop the framework In use, vibrations resulting from rotation of the cc shaft 11, set up harmonic vibrations within the housing Such vibrations are transmitted by way of the housing, the 16 additional tubular supports 19, and the diaphragms 17, 18 to the sieve bend 23 over its length and breadth, thereby giving an even distribution of vibration across the entire screening surface. In addition, minimal vibrational energy is lost to the support framework 39 in view of the box being suspended in polyurethane mouldings 32, 33 and the apparatus being isolated from the box by polyurethane securements 24, 0: Such an arrangement overcomes the problems of rapid wear associated with previous vibrating screens and greatly extends the working life of the sieve screen.

Whilst the above has been given by way of illustrative example of the invention, many modifications and variations may be made thereto by persons skilled in the art without departing from the broad scope and ambit of the invention as herein set forth in the following claims.

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Claims

2. Apparatus for vibrating a sieve bend as claimed in claim 1, which is suspended on a framework. *f*
3. Apparatus for vibrating a sieve bend as claimed in claim 2, wherein suspension is by means of chains connected to blocks of resiliently deformable material attached to the e* 6 framework.
4. Apparatus for vibrating a sieve bend as claimed in o* any one of the preceding claims, wherein the housing in which the rotatable shaft is located is a tubular metal pipe. Apparatus for vibrating a sieve bend as claimed in any one of the preceding claims, wherein the rotatable shaft is weighted on one end so as to set up an imbalance upon i is weighted on one end so as to set up an i h eupon /12 LA 12 rotation which results in vibrational motion in the housing.
6. Apparatus for vibrating a sieve bend as claimed in any one of the preceding claims, wherein the diaphragm comprises a metal plate or plates welded to the housing.
7. Apparatus for vibrating a sieve bend as claimed in claim 6, wherein there are two metal plates which are equally spaced from the ends of the housing and from one another.
8. Apparatus for vibrating a sieve bend as claimed in any one of the preceding claims, wherein the at least one diaphragm is also connected to supports which extend parallel to the housing on each side thereof.
9. Apparatus for vibrating a sieve bend as claimed in any one of the preceding claims and including a secondary &*so vi'brator located on a plate fixed to the at least one **so diaphragm. **G0 A vibratory sieve bend comprising an apparatus as claimed in any one of the preceding claims in combination with a sieve bend.
11. Apparatus for vibrating a sieve bend substantially 6* so o as herein described with reference to the accompanying 6 drawings. 4 12. A vibratory sieve bend substantially as herein described with reference to the accompanying drawings. 00 00 *DATED this 11th day of )ecember 1989 SCREEN MANAGEMENT CONSULTANTS PTY LTD By their Patent Attorneys G.R. CULLEN CO.